Question about the dmg of poison. Why is the dmg reduced?

[georgecorbett]

Hi, I have a question about the dmg poison on my assassin. In the main card, I have 15000 to 23000, but if I take the second item with poison 35-75 1 second, my dmg will drop to 10000. And if I take the 3rd it will decrease even more. Can anyone explain it to me?
Thanks!

[Jampula]

This explains pretty much everything about poison:
viewtopic.php?f=40&t=70559